The present system and method relate generally to vehicular drivelines. More specifically, the present system and method relate to reducing the torque transferred from an engine to a transmission portion of a vehicular driveline.
Automobile manufacturers are constantly working to improve fuel efficiency in motor vehicles. Improvements in fuel efficiency for larger vehicles, such as vehicles that incorporate diesel or other large engines, often translate to a reduction in the engine speed. Consequently, recent developments in the design of vehicular drivelines for larger vehicles have resulted in drivelines exhibiting relatively low engine speeds.
While a reduction in engine speed does increase fuel efficiency in larger vehicles, the decrease in engine speed takes a toll on driveline components. For example, a reduction in engine speed results in a corresponding increase in torque transferred through the driveline. Prior art powertrain systems were not sized to handle the maximum torque loading that often occurs at low-speed operation. Specifically, the effective life of transmissions associated with traditional powertrain systems is reduced as a result of the lower engine speeds. Consequently, current drivelines for larger vehicles are often limited in horsepower output by the amount of torque that can be handled by the powertrain transmission. Additionally, the increase in torque provided by the engines operating at lower speeds increased the amount of torque absorbed by the powertrain clutches during shift events. That is, with an increase in powertrain torque, engagement of a powertrain clutch meant transferring an increased amount of torque to the clutch, causing increased wear and lower effective life.